Type 2 diabetes (T2D) is chronic disease characterized by high blood glucose and rapidly emerged as a global health care problem that threatens to reach pandemic levels by 2030. Nearly 350 million people worldwide are currently affected by diabetes. Diabetes is a major cause of heart disease and stroke and also leads to other complications, such as vision loss, kidney failure, and amputations of legs or feet. The effective drugs for treatment of T2D, such as insulin and glucagon-like peptide 1 (GLP- 1), require injections, which are inconvenient and expensive. Development of safer, more effective, and more convenient oral medicines, therefore, will be necessary for preventing the diabetes pandemic. The product of this SBIR is the oral dosage form of DT-109 for the treatment of T2D. DT-109 is a tripeptide that effectively lowered blood glucose in several T2D mouse models by increase the GLP-1 and insulin levels when orally administered. Since DT-109 is comprised of natural occurring L-amino acids, it is considered to be a safer, cheaper, and a convenient pharmaceutical intervention for T2D patients. The long-term goal of this SBIR is to complete preclinical development and identify a partner or investor consortium to fund clinical trials for DT-109 as an oral therapeutic for T2D. Diapin Therapeutics has demonstrated that DT-109 acts through a G-protein coupled receptor (GPCR) to elicit its activity and high throughput screening of GPCR libraries showed the 3 hits as an agonist among 160 GPCRs. This phase I hypothesis is that at least one of 3 GPCRs are essential for DT-109 to elicit its activity. There are two specific aims in this phase I SBIR proposal. Aim 1 is to confirm the results from high throughput screening and identify the specific GPCR(s) required for the effect using a gain-of-function model. Aim 2 is to determine the functional importance of the GPCR(s) using a loss-of-function model. Characterization of the MOA of DT-109 is critical for our understanding of the pharmacology of DT-109. The phase II of this SBIR will carry on the studies on pharmacokinetics/toxicokinetics and complete the data set for opening IND for DT-109. The patent for the oral dosage form of DT-109 has been issued and the identification of DT-109 targets will help us to bridge with big Pharmas to open clinical trials for DT-109 as an oral therapeutic for T2D.